Suspension seats for commercial and recreational vehicles can reduce the forces experienced by operators or passengers as the vehicles move while travelling over rough surfaces. An example application of suspension seats is in fast boats travelling in rough water. A typical suspension seat comprises a first portion and a second portion movable relative to the first portion. An isolator, such as a coil-over shock absorber or an air-shock absorber, mitigates relative movement between the first and second portions. The first portion is attached to a vehicle surface, and the second portion is attached to a seat. Forces applied to the first portion as the vehicle bounces (e.g. as a boat moves through water) are mitigated by the isolator, such that the magnitude of these forces transferred to a person supported by the second portion is limited.
The mechanism which allows relative motion of the first and second portions of a suspension seat may include one or more bushings to reduce the coefficient of friction between the two portions as they move relative to each other. Such bushings are known in the art, and have several disadvantages. For example, a bushing can quickly become worn through its contact with the first and second portions. Bushing wear can be amplified by the side-loading that a seat may experience on some vehicles, such as boats which encounter waves from various directions. Such wear of the bushings may allow the second portion to move radially or angularly relative to the first portion. This element of “play” is undesirable, as it may affect the integrity of the first and second portions. There remains a need for a long-lasting means of limiting friction and radial or angular movement between the portions of a suspension seat.
Some suspension seats may be rotatable, while some may be fixed into a particular rotational position about a longitudinal axis. Suspension seats which are fixed generally comprise a block stop on the second portion, which sits in a corresponding slot in the first portion. Over time, as the block stop rubs against the edges of the slot in order to prevent the second portion from rotating, the block stop may become worn, such that more and more relative rotational motion is allowed between the first and second portions. There remains a need for long-lasting means of preventing rotation in suspension seats.
In addition, suspension seats are generally provided in models which have a fixed range of heights. The first portion of the suspension seat is at a permanently fixed height once it is installed, thereby limiting the height range of the suspension seat. Typically, if it is desired to have a suspension seat at a certain height from the vehicle surface, a specific model of suspension seat having a height range which includes that specific height must be employed. If a model of suspension seat that can be adjusted to provide the desired height is not offered or available then the vehicle owner may be forced to make alterations to the first portion of the suspension seat or to the vehicle to achieve the desired height. There remains a need for a suspension seat with a wider range of available heights.